速比对混合层湍流参数影响的实验研究

本文使用PIV术对低高速侧速比为0.25、0.33和0.5时竖直通道内的混合层流动进行实验研究,基于速度差和通道水力直径的雷诺数范围15840～132000.研究发现混合层内湍流参数的分布不仅和雷诺数有关,还和速比有关.混合层内同一横截面上平均雷诺应力的最大值随雷诺数的增大而增大,而在同一横截面上相同雷诺数时雷诺应力的最大值则随速比的增大而减小.在同一横截面上平均涡量随雷诺数的增大而增大,雷诺数相同时平均涡量的最大值随速比的增大而增大.无量纲平均涡量的最大值随混合层的发展按指数规律衰减,速比越大衰减速度越快.

EFFECTS OF VELOCITY RATIO ON TURBULENT MIXING LAYER

In present paper,the effect of velocity ratio on plane mixing layer is experimentally investigated with Particle Image Velocimetry(PIV).The velocity ratio between low-and high-speed side are 0.25.0.33 and 0.50.respectively.The Reynolds number based on the velocity difierence of two streams and hydraulic diameter of the channel ranges from 15840～132000.The results indicate that the maximum mean Reynolds stress on the same cross section increases with Reynolds number increasing but decreases with velocity ratio increasing at the equal Reynolds number.The mean vorticity increases with Reynolds number increasing on the same cross-section and increases with the velocity ratio increasing at the equal Reynolds number.The maximum non-dimensional mean vorticity decreases according to an exponential law along the stream-wise direction,and the decreasing speed of maximum mean vorticity increases with the velocity ratio increasing.